Drawn rod or wires for industrial purposes can be made from a variety of metals or alloys including without limitation aluminum, copper, alloy steels, and carbon steels. When made using a carbon steel, the carbon content can range from about 0.35 to 1.1% by weight. Carbon steel may also contain alloying elements such as chromium (Cr), boron (B), silicon (Si) or combinations of these elements.
Before drawing, a material is usually subjected to a heat treatment known as annealing. For carbon steel, the heat treatment consists of passing a rod or wire through a heat source such as a furnace to heat the rod or wire to about 930° C. to 1020° C. This high temperature treatment produces a uniform face centered cubic austenite phase with a regulated grain size to help determine the product's subsequent ductility. Subsequent cooling in air or more commonly in molten lead or fluidized sand produces a phase transformation from face centered cubic austenite to body centered cubic ferrite and orthorhombic cementite arranged in alternating plates, jointly called pearlite. This transformation is rapid since the sections treated are relatively small (generally less than 3.5 mm). The resulting structure consists of very fine pearlite preferably with no grain boundary ferrite or cementite. The fineness of the pearlite depends on the product chemistry and the temperature to which the product is reduced after austenitizing. As annealed, fine pearlite rod or wire is able to be drawn to reductions of area up to and sometimes exceeding 97%, resulting in very high drawn filament strengths. The final drawn filament strength provides exceptional fatigue resistance due to the very fine pearlite size, superior surface quality and the alignment of cementite plates in the drawn direction.
Heat processing metal objects by a fluidized bed is known where the temperature of a solid medium, such as sand suspended in a gas is used to regulate the rate of heat transfer. The rate of heat transferred to the surrounding media per unit surface area of the rod or wire is determined by the temperature of the media since the convective heat transfer coefficient is constant for the media chosen.
Heat processing metal objects by means of a liquid lead bath or media is also known where the temperature of the liquid lead is used to regulate the rate of heat transfer. The rate of heat transferred to the surrounding media per unit surface area of the wire is determined by the temperature of the media.
Heat processing metal objects by means of air is also known where the temperature and velocity of the air is used to regulate the rate of heat transfer.
However, once the physical characteristics of fluidized sand or molten lead baths are set, the flexibility of the heat treating process becomes limited. When processing strand products of different chemistries, like SAE 1070 and SAE 1090 steels requiring different quenching temperatures, it is not possible to accommodate both since only a single temperature can be maintained in any one quenching zone or bath.
Metal alloys such as steel alloys are produced with many different characteristics for use in different industries for different purposes. In recent years, a large demand has developed for steel strands or wires for use in industrial applications such as vehicle tires, bridge strands, pre-stressed strands, galvanized drawn wire, music wire, saw wire and other products to improve their durability and strength. For vehicle use, such tires are generally referred to as steel belted radials, which are realized as stronger and last much longer than conventional, non-belted tires.
Various companies manufacture tire wire cord for use by tire manufacturers which are generally supplied on spools and designate standard alloys of SAE 1070, 1080, 1090, and non-standard alloys designated 1090Cr, 1090B, 1090CrB, and 1080SiCr with a breaking load commensurate with the type of steel used and the total amount of area reduction during final drawing.
After prolonged use, it is not uncommon for some of the wires in steel belted tires to wear, fatigue, and break. Tire manufacturers and suppliers have sought to improve the quality of steel belted tires by changing their manufacturing techniques and testing other, more expensive steel compounds, wire diameters and the like with varying results.
In view of the foregoing, it would be highly desirable to provide a new and improved rod or wire manufacturing system, a new and improved heating-cooling operation, a new and improved cooling unit, a new and improved method for manufacturing a rod or wire, and/or a new and improved rod or wire while addressing the above described shortfalls of the art systems.